Chapter 12

The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

Part 2

Gypsy moth controlEntomorphaga

Ceratocystis ulm (Dutch elm disease)

Taxol productionTaxomyces

Cryphonectria parasitica (chestnut blight)

Cellulose used for juices and fabric

Trichoderma

Food spoilage

Negative Effects

Bread, wine, beerSaccharomyces

Positive EffectsFungi

Economic Effects of Fungi

• Used in biotechnology, biological pest controls vs. undesirable effects

• Mutualistic combination of an alga (or cyanobacterium) & fungus– Classified according to the fungal partner (most

often an ascomycete)– Mutualism: a type of symbiosis in which both

organisms or populations are benefited

• Alga produces and secretes carbohydrates (via photosynthesis), fungus provides holdfast (enclose alga)

• Some of the slowest growing organisms on Earth

Lichens

Lichens

Figure 12.10

Lichens

• Often the first life forms to colonize newly exposed soil or rock– Colonize habitats that are unsuitable for either

the alga or the fungus alone

• Grouped into 3 morphologic categories– Crustose, foliose, and fruiticose

• Used as dyes for clothing, an antimicrobial agent, the dye in litmus paper; cause allergic contact dermatitis

Algae

• Unicellular, filamentous, or multicellular

• Mostly aquatic (in cool temperate waters); some found in soil or on trees

• Eukaryotic photoautotrophs (lack tissues)– Oxygenic photosynthesis– Chlorophyll a and accessory pigments

• Absorb nutrients from water

• Identification by microscopic examination

Algae

• Classification by rRNA sequences, structures, pigments, and other qualities

• Reproduce asexually (fragmentation and cell division) and some can reproduce sexually (triggered by environmental condition)

• Selected Phyla of Algae – Brown algae (kelp), red algae, green algae,

diatoms, dinoflagellates, and water molds

Figure 12.11a

• Brown algae (kelp)

• Multicellular; macroscopic

• Cellulose + Alginic acid cell walls

• Chlorophyll a and c, xanthophylls

• Store carbohydrates

• Harvested for algin

Phaeophyta

Figure 12.11b

• Red algae

• Grow at deeper depth in ocean

• Cellulose cell walls

• Most multicellular

• Chlorophyll a and d, phycobiliproteins

• Store glucose polymer

• Harvested for agar and carrageenan

Rhodophyta

Figure 12.11c

• Green algae

• Cellulose cell walls

• Unicellular or multicellular; most are microscopic

• Chlorophyll a and b

• Store glucose polymer (starch)

• Gave rise to terrestrial plants

Chlorophyta

Figure 12.12a

• Diatoms

• Pectin and silica cell walls

• Unicellular or filamentous algae

• Chlorophyll a and c, carotene, xanthophylls

• Store oil

• Fossilized diatoms formed oil

• Produce a neurotoxin (domoic acid)

Bacillariophyta

Figure 12.13

• Dinoflagellates

• Cellulose in plasma membrane

• Unicellular; collectively called plankton

• Chlorophyll a and c, carotene, xanthins

• Store starch

• Cause red tide (Alexandrium)

• Neurotoxins cause paralytic shellfish poisoning & ciguatera

Dinoflagellata

Figure 12.14

• Water molds

• Cellulose cell walls

• Multicellular

• Chemoheterotrophic

• Produce zoospores

• Decomposers and plant parasites– Phytophthora infestans responsible for Irish potato

blight– P. cinnamomi infects Eucalyptus– P. ramorum causes sudden oak death

Oomycota

Figure 12.15

Roles of Algae in Nature

• Important part of aquatic food chain (fix CO2 into organic molecules that can be consumed by chemoheterotrophs) = primary producer– Primary producer: an autotrophic organism, either

chemotroph or phototroph, that converts CO2 into organic compounds

• Estimated that 80% of the Earth’s O2 is produced by planktonic algae

Roles of Algae in Nature

• Seasonal red tide (blooms of dinoflagellates) and algal blooms

• Much of world’s petroleum formed from fossil remains of diatoms and other planktonic organisms

• Symbiotic relationship between unicellular algae and animals e.g. giant clam

• Unicellular and mostly aerobic

• Eukaryotic chemoheterotroph

• Inhabit water and soil; some are part of the normal microbiota of animals

• Vegetative form is a trophozoite (feeding and growing stage)– Trophozoite feeds upon bacteria and small

particulate nutrients

• Asexual reproduction by fission, budding, or schizogony (multiple fissions)

Protozoa

Protozoa

• Sexual reproduction by conjugation (protozoan) e.g. Paramecium

• Some produce cysts– Allows organisms to

survive under adverse condition or outside a host

– Oocyst: reproductivestructure in which new cells are produced asexually

Figure 12.16

Protozoa

• Some have a protective covering (pellicle)

• Ciliates take in food by waving their cilia toward a mouth like opening (cytostome)

• Amoebas engulf food by extending pseudopods around it and phagocytize it

• Digestion occurs in membrane-enclosed vacuoles

• Waste eliminated through plasma membrane or through anal pore

• No mitochondria

• Multiple flagella

• Giardia lamblia

• Trichomonas vaginalis (no cyst stage)

Archaezoa

Figure 12.17b-d

• No mitochondria

• Nonmotile due to lack of microtubules

• Obligate intracellular parasites

• Cause of a number of human diseases, esp.. in AIDS patients

• Nosema

Microspora

• Move by pseudopods

• Entamoeba

• Acanthamoeba

Rhizopoda (amoebas)

Figure 12.18a

• Nonmotile in their mature form

• Intracellular parasites

• Characterized by the presence of a complex of special organelles at the tips of their cells

• Complex life cycles – definitive host (harbors sexually mature adult) and

intermediate host (harbors the larval or asexual stage)

• Plasmodium, Babesia, Cryptosporidium, & Cyclospora

Apicomplexa

• Move by cilia

• Complex cells

• Balantidium coli is the only human parasite

Ciliophora (ciliates)

Figure 12.20

• Move by flagella• Lack sexual reproduction• Photoautotrophs

– Euglenoids (pellicle)• Chemoheterotrophs

– Naegleria • Flagellated and amoeboid forms, meningoencephalitis

– Trypanosoma• Undulating membrane, transmitted by vectors

– Leishmania• Flagellated form in sand fly vector, ovoid form in

vertebrate host

Euglenozoa

Euglenozoa

Figure 12.21

• Cellular slime molds

(Fig. 12.22)– Resemble amoebas,

ingest fungi & bacteria by phagocytosis

– Cells aggregate into stalked fruiting body.

– Some cells become spores

Slime Molds

• Plasmodial slime molds (Fig. 12.23)– Multinucleated large

cells (protoplasm)– Cytoplasm separates

into stalked sporangia – Nuclei undergo

meiosis and form uninucleate haploid spores

• Have fungal and amoebal characteristics

Helminths

• Free-living worms and parasitic worms– Flatworms or roundworms

• Eukaryotic multicellular animals

• Adult can be monoecious (hermaphroditic) or diecious (two separate sexes)

• Parasitic helminths – Lack a digestive system– Have reduced nervous system– Have reduced or completely lacking means of

locomotion

Helminths– Complex reproductive system (definitive and

intermediate hosts)

• Helminths (parasitic worms)– Phylum: Platyhelminthes (flatworms)

• Class: Trematodes (flukes) (Fig. 12.26)

• Class: Cestodes (tapeworms) (Fig. 12.28)– Both classes absorb nutrients through nonliving outer covering

(cuticle)

– Cause disease in a wide varieties of animals

– Phylum: Nematodes (roundworms)• Have a complete digestive system

• Either eggs can be infective (pinworm) or larva can be infective (adult hookworms)

Trematodes (flukes)

Figure 12.25

Cestodes (tapeworms)

Figure 12.27

Nematodes: Eggs Infective for Humans

Figure 12.29

Nematodes: Larvae Infective for Humans

Figure 25.26

• Kingdom: Animalia– Phylum: Arthropoda

(segmented bodies, exoskeleton, jointed legs)• Insecta (6 legs)

– Lice, fleas, mosquitoes, flied, bees

• Arachnida (8 legs)– Mites, ticks, spiders

– May transmit diseases (vectors)

• Crustacea (4 antennae)– Crabs, crayfish

Arthropods as Vectors

Figure 12.31, 32

Arthropods as Vectors

• Vectors: arthropods that carry pathogenic microorganisms– Some parasites multiply in their vectors– Some vectors are a mechanical means of

transport– a few arthropods suck blood and transmit

microbial diseases while doing that

• Elimination of vectorbone disease by eradication of the vectors

Table 12.1

Chapter Review

Chapter Review

• Eukaryotic microorganisms: fungi, lichens, algae, protozoa, slime molds, and helminths

I. Fungi

• Mycology: the study of fungi

• Eukaryotic (yeast, molds, mushrooms, etc.)

• Aerobic to facultative anaerobic

• Chemoheterotrophic

• Few are plant and human pathogens

Fungi

• Usually grow better in acidic environment (about pH = 5)

• Require less nitrogen for growth

• More resistant to osmotic pressure (high salt or sugar concentration)

• Can grow on a very low moisture surface

• Capable of metabolizing complex carbohydrates

Fungi • Most decompose organic matter (dead plant

matter) to inorganic molecules– Recycle vital elements– Absorb nutrients instead of ingestion

• Molds and fleshy fungi– Multicellular; aerobic– In a clinical lab, identified by 1) colony morphoogy, 2)

type of phyphae (septate or coenocytic), and 3) type of asexual spores formed (at the tip of aerial hyphae)

Fungi

– For taxonomy (classification), type of sexual spores are used

• Yeasts– Unicellular; facultative anaerobe– Fermentation used in brewing, wine-making, and

baking– Yeast identification in a clinical laboratory based

on biochemical tests– Pathogenic dimorphic fungi have yeastlike form

at 37 oC and moldlike form at 25oC

Fungi• Fungal Diseases (Mycoses)

– Tend to be chronic (long-lasting) due to slow growth and harder to treat since fungi are eukaryotes

• Effects of Fungi– Used in biotechnology & biological pest controls;

cause food spoilage– Used as foods; used to produce foods or drugs– Human pathogens (4 phyla): Zygomycota,

Ascomycota, Basidiomycota, & Anamorphs (formerly Deuteromycota); plant pathogens

Lichens• Mutualistic combination of an alga (or cyano-

bacterium) and fungus (most often an ascomycete)– Mutualism: a type of symbiosis in which both

organisms or populations are benefited– Alga produces and secretes carbohydrates &

fungus provides protection & holdfast

• Classified according to their fungal partner

• Used as dyes for clothing, dye in litmus paper, an antimicrobial agent; cause allergic contact dermatitis

Algae

• Unicellular, filamentous, or multicellular

• Mostly aquatic (in cool temperate waters); some found in soil or on trees

• Eukaryotic photoautotrophs (lack tissues); absorb nutrients from water– Oxygenic photosynthesis

• Reproduce asexually (fragmentation and cell division) and some can reproduce sexually (triggered by environmental condition)

Algae

• 5 Phyla of Algae– Brown algae (kelp): macroscopic; in coastal

waters; harvested for Algin (thickner for foods, rubber tires and hand lotion)

– Red algae: grow at deeper depth in ocean; provide agar (used in microbial media) & carrageenan (a thickening ingredient in evaporated milk, ice cream, and pharmaceutical agents)

– Green algae: believed to have given rise to terrestrial plants

Selected Phyla of Algae

– Diatoms: unicellular or filamentous algae with complex cell walls (pectin & silica); store energy captured through photosynthesis as oil; some produce a neurotoxin (domoic acid)

– Dinoflagellates: unicellular algae collectively called plankton (free-floating organisms); cause red tide; some produce neurotoxins (cause ciguatera and paralytic shellfish poisoning)

– Water molds (oomycota): decomposers; form cottony masses on dead algae and animals (in fresh water); terrestrial oomycotes are plant parasites

Algae• Roles of Algae in Nature

– Important part of aquatic food chain; primary producers (fix CO2 into organic molecules that can be consumed by chemoheterotrophs)

– Estimated that 80% of the Earth’s O2 is produced by planktonic algae

– Much of world’s petroleum formed from fossil remains of diatoms and other planktonic organisms

– Cause red tide– Symbiotic relationship between unicellular algae

and animals (e.g. giant clam)

Protozoa

• Unicellular, eukaryotic chemoheterotrophic organisms

• Inhabit water and soil; some are part of the normal microbiota of animals

• Trophozoite: the feeding and growing stage; feeds upon bacteria and small particulate nutrients

• Reproduce asexually by fission, budding, or schizogony (multiple fission)

Protozoa

• Some reproduce sexually (e.g. Paramerium via protozoan conjugation)

• Some produce a protective capsule (cyst) under certain adverse conditions– Encystment allows organisms to survive when

food, moisture, or oxygen are lacking– Also allows a parasitic species to survive

outside a host– oocyst: reproductive structure in which new

cells are produce asexually

Protozoa• Medically Important phyla

– Archaezoa: lack mitochondria; many live as symbionts in the digestive tracts of animals; most have two or more flagella

– Microspora: lack mitochondria & microtubules; obligate intracellular parasites; cause of a number of human diseases, esp. in AIDS patients

– Rhizopoda (amoebas): pseudopods used for movement and engulfing food; some are pathogenic

Protozoa– Apicomplexa: non-motile, and obligate

intracellular parasites in their mature forms; complex life cycle (definitive and intermediate hosts) e.g. Plasmodium (cause malaria)

• Definitive host: harbors sexually mature adult parasite vs. Intermediate host: harbors the larval or asexual stage

– Ciliophora (ciliates): have cilia that are moved in unison to propel the cell for movement and to bring food particles to the mouth; e.g. Balantidium coli (human pathogen)

– Euglenozoa: have flagella and lack sexual reproduction

Slime Molds

• Have fungal and amoebal characteristics (more closely related to amoeba)

• Two phyla: cellular and plasmodial slime molds– Cellular slime molds: resemble amoebas; asexual

reproduction only; large numbers of amoeboid cells aggregate to form a single structure that is enclosed in a slimy sheath (slug) (Fig. 12.22)

– Plasmodial slime molds: exists as a mass of protoplasm with many nuclei (multinucleated); sexual and asexual reproduction

Helminths• Free-living worms and parasitic flatworms

or roundworms

• Multicellular eukaryotic animals

• Parasitic helminths generally lack a digestive system (exception does exist); have reduced nervous system; have reduced or completely lacking means of locomotion; complex reproductive system; need definitive and intermediate hosts

Helminths• Platyhelminthes (flatworms): flukes &

tapeworms– Cause disease in a wide variets of animals– Absorb nutrients through nonliving outer

covering (cuticle)– Use suckers for attachment– Humans can be definitive or intermediate hosts

• Nematoda (roundworms)– Have a complete digestive system– Human infection: either egg is infective or larva

is infective

Arthropods as Vectors

• Arthropods: characterized by segmented bodies, hard external skeletons, and jointed legs; largest phylum in the animal kingdom

• Representative classes of arthoropods– Arachnida: spiders, mites, ticks– Crustacea: crabs, crayfish– Insecta: bees, flies, lice

• Vectorborne diseases is eliminated through eradication of the vectors

Arthropods as Vectors

• Vectors: arthropods that carry pathogenic microorganisms– a few arthropods suck the blood of humans and

other animals and can transmit microbial diseases while doing that

– Some vectors are just a mechanical means of transportation e.g. houseflies

– Some parasites multiply in their vectors & parasites accumulate in the vectors feces or saliva e.g. Lyme disease & West Nile virus, Plasmodium

Chapter Review

• Know these terms: mycology, mycoses definitive host, intermediate host, vector (arthropod), and trophozoite.

• Know the roles of fungi in nature and characteristics of fungi. Also know why fungal disease are harder to treat than bacterial diseases

• Know characteristics of lichens.

Chapter Review

• Know the roles of algae in nature.

• Know the function of cyst or encystment for protozoa. Know the characteristics of medically important protozoa.

• Know the characteristics of slime molds.

• Know the characteristics of parasitic helminths.